Investigations are designed to isolate and characterize the plasma membrane receptor for epidermal growth factor (EGF). Detergent solubilized receptors have been obtained, although high affinity binding of 125I-EGF is decreased 10-fold. Various reactivation procedures, such as the addition of phospholipids, will be carried out. Purification of the soluble EGF receptor will be effected primarily by affinity chromatography. Various physical, kinetic and chemical properties of the receptor also are to be studied. Anti-sera to preparations of membranes containing high levels of EGF receptors have been obtained and block 125I-EGF binding. Further experiments will be conducted to try to isolate antibody to the EGF receptor from these antisera and to study how antibodies interact with the EGF receptor. Another area of investigation of EGF receptor activity will include determination of receptor binding levels in human skin tissue obtained from clinical biopsies. The skin biopsies will be classified as to the degree of hyperplasia with or without the presence of malignancy prior to assay for receptor activity.